Developmental dysplasia or dislocation of the hip (DDH) is an abnormal development of the hip joint usually identified in infants and children. In all cases of DDH, the acetabulum (the hip socket) is shallow and the ball of the femur is not stable within the hip socket. However, the severity of DDH can vary from patient to patient. To improve the condition, the hip joint is usually arranged in a position to encourage proper growth for a period of time. Frequently a cast or harness is used to maintain this prescribed position for a period of weeks or months.
The different types of restraints used to keep patients in the therapeutic position vary depending, in part, on the severity of the DDH and the age of the child. One common restraint is the spica cast. The spica cast is a typical hard-sided cast that is generally applied from the waist area to the knees of the patient in an effort to keep the hip joint immobilized in the preferred therapeutic position. Because the spica cast is cumbersome to apply while the patient is in the therapeutic position, the spica cast is typically applied while the patient is under general anesthesia.
Because DDH is often diagnosed and treated in patients that are young and not toilet-trained, special care must be taken when applying the spica cast to allow for diapering of the patient. However, despite the best efforts of parents and caregivers, the spica cast frequently gets soiled with urine and feces. Soiled spica casts can create skin conditions for the patient. A soiled cast that makes contact with the skin can cause rapid skin breakdown leading to discomfort, painful sores, rashes, and other skin conditions. Because the spica cast is generally worn for 6 to 12 weeks at a time, the child must either be left in a soiled cast which may cause skin irritation or have a new cast applied which may require general anesthetic. It is desirable therefore, to have a cast that can be removed and cleaned or replaced when soiled but that does not require anesthesia or significant discomfort to the patient during removal and re-application.